Highlights from Recent Cancer Literature
Journal: Cancer Research (2012)

An Aspirin a Day. ..?Three articles published simultaneously online in The Lancet from Peter Rothwell and collaborators have substantially increased our understanding of the potential of aspirin in cancer prevention.Many studies show that daily aspirin may reduce incidence of and death from colorectal cancer.Effects on other cancers are not as well established, however, due to inadequate numbers of cases studied.Hence, in the first of the 3 articles, Rothwell and colleagues report their results from a systematic review of case-control and cohort studies over the past 60 years that had revealed associations between aspirin use and risk or outcome of cancer.Overall, the eligible articles described 41,575 cancers during 39,981,678 personyears of follow-up.Regular use of aspirin was again associated with a consistent reduced risk of colorectal cancer, and these findings were in good agreement with published data from randomized trials.Consistent reductions were also seen in risk of esophageal, gastric, biliary, and breast cancer.Again, estimates of the effect of aspirin on individual cancers in case-control studies were strongly correlated with those in previously reported randomized trials.Regular use of aspirin was associated with a reduced proportion of cancers with distant metastasis but not with any reduction in regional spread, consistent again with previous findings in randomized trials.The next article addressed early rather than long-term effects of daily aspirin in randomized trials.The results showed that cancer deaths were significantly reduced in participants in the aspirin arm of the trial, particularly from 5 years onwards.Rothwell and colleagues then analyzed 6 trials of daily low-dose aspirin with 35,535 participants and found that the effects of aspirin were seen as early as 3 years.The reduced risk of major vascular events on aspirin was initially offset by an increased risk of major bleeding, but effects on both outcomes diminished with increasing follow-up, leaving only the reduced risk of cancer after 3 years.Because the effects of aspirin on mortality appear after only a few years, it would seem likely that daily aspirin might also reduce cancer growth or metastasis.In the third article, the authors used the data from 5 large randomized trials of daily aspirin use that have been conducted in the United Kingdom, representing a total of 17,285 participants.Among these participants, 987 people developed a new solid cancer during the trial, and their histories were studied in detail.Those taking aspirin had a reduced risk of cancer with distant metastasis.Aspirin also reduced the risk of metastasis at initial diagnosis and on follow-up.Assignment to the aspirin cohort also reduced death due to cancer in patients who developed adenocarcinoma, particularly in those without metastasis at diagnosis.Consequently, aspirin reduced the overall risk of fatal adenocarcinoma in the trial populations.These effects were independent of age and sex, but the benefit was greatest in smokers.These results suggest that aspirin might help in treatment of some cancers, especially to prevent distant metastasis.Alongside the previously reported reduction by